1. Field of the Invention
This invention relates to an air filter, more particularly to an air filter capable of visual indication of a clogged condition thereof.
2. Description of the Related Art
A conventional air filter including a filter unit for filtering air flowing through the air filter is known in the art. However, prolonged operation of the air filter in a clogged condition of the filter unit will lead to a low air-filtering efficiency and may result in breakdown of a fan unit of the air filter.
Therefore, the object of the present invention is to provide an air filter capable of visual indication of a clogged condition thereof, thereby permitting timely maintenance of the air filter.
According to this invention, the air filter capable of visual indication of a clogged condition thereof includes a housing, a filter unit, a fan unit and a signaling device. The housing has an air inlet, an air outlet, and an air passage extending from the air inlet to the air outlet. The filter unit is mounted on the housing for filtering air flowing through the air passage. The fan unit is mounted in the housing for drawing air into the air passage via the air inlet and for blowing air out of the air passage via the air outlet. The signaling device includes a flap disposed to span the air passage, a horizontal pivot pin connected securely to the flap and pivotable relative to the housing, and a pointer connected to one end of the pivot pin and rotatable with the pivot pin relative to the housing. Air flow through the air passage in an unclogged condition of the air filter blows the flap to pivot and cause the pivot pin to rotate and move the pointer to a first position relative to the housing. A reduction in the air flow through the air passage attributed to a clogged condition of the air filter causes the flap to pivot and move the pointer to a second position relative to the housing so as to indicate the clogged condition of the air filter.